Head lamp



Feb. 6, 1940. R. w. cARLlsLE HEAD LAMP Filed Sept. 24, 1956 2Sheets-Sheet 1 INVENTOR M4 11/ Feb. 6, 1940. R. w. CARLISLE 9,

HEAD LAMP Filed Sept. 24, 1936 2 Sheets-Sheet 2 Ha Z/a Fig. q

INVENTOR I fi 7% TORNEY Patented Feb. 6, 194-0 UNITED STATES PATIENTOFFICE 2,189,164 HEAD mil Richard Wallace Carlisle, Flushing Heights, N.Y. Application September 24, 1936, Serial No. 102,288

Such stray light if it causes the sensation of brightness to an oncomingobserver is called glare. The sensation of glare is proportional to 15themaximum intensity of light received by the observer's eyes. i i

In incandescent lamps of this class constructed according to the priorart, it has been common to utilize light-shielding members disposed in20 front of the filament for the purpose of preventing light frompassing directly from the source to the observers eyes. In every case inwhich glare has been appreciably reduced, however,

a large percentage of the total light has been 25 wastefully interceptedby these shields.

This invention utilizes a plurality of light shades which do notintercept light rays by reason of being always either parallel to oroutside of the direct beam, but diffuse or minimize the rays passingfrom the light source to points above the region illuminated by thebeam.

It is one object of this invention to provide means for reducing themaximum intensity of light impressed upon an observer's eyes by a 35vehicle lamp while still operating the lamp at um efliciFncy. 1

It is another object of this invention to provide means to illuminatethe side'of the road removed from an coming vehicle more strongly it)than that side on w ichsaid vehicle is approachi s. in order to show thedriver his edge of the road for his own guidance and for the protectionof pedestrians there.

Another object of this invention is to make a 45 compact assembly of alight source with glarepreventing means constructed according to theprinciples of this invention by placing said .glare prevention meansinside the bulb of an incandescent lamp in closely spaced relationshipto one or more filaments.

The principal ways in which light shields may be mounted according tothis invention in front of a parabolic reflector with their surfaces allsubstantially parallel to the beam therefrom are 55 illustrated in thedrawings, in which:

10 Claims. (Cl. 176-26) Fig. 1 is a sectional view of an incandescentlamp inside of which a plurality of-glare preventing shells has beenmounted.

Fig. 2 is a side elevation of an incandescent lamp bulb inside of whicha curved lightshield has been mounted: a

Fig. 3 is a front elevation of the incandescent lamp bulb shown in Fig.2; V

Fig. 4 is a side elevation of a double filament incandescent bulb usinga. plurality of flat light Y intercepting shields;

Fig; 5 is a front elevation of the bulb shown in 4;

Fig. 6 is a side elevation of an incandescent lamp having a curved, anda straight intercept- 16 ing shield;

Fig. 7 is a front elevation of the lamp in 4 Fig. 6; r

Fig. 8 is a side elevation of an incandescent lamp having flat lightintercepting shields; and

' Fig. 9 is a front view of the lamp shown in Fig. 8. r I

Fundamental structure The arrangement of shells shown in the upper halfof Fig. 1 comprises the structure fundamental to the principles of thisinvention for preventing glare to any observers located above the top ofa horizontally projected beam.

, All the embodiments of my invention are shown in the drawings asmodifications of -a standard type of headlamp comprised of a lamp bulbB, mounted at the focus of a parabolic reflector P.

- Principles of optical action The optical action of this device asshown in Fig. -1 is as follows: Rays RI, R2 and R3 emanating from thelight source by their reflection from the parabolic reflector P arecaused to assume a "direction parallel to the axis of the reflector. 40

The aggregate of these rays comprises the direct beam of the headlamp,which is not a source of glare except when thrown directly into theobserver's eyes by an upward tilting movement such as might be caused byundulations in a highway.

Assuming that the parabolic reflector is ac-. curately made andproperlyfocussed, the only rays which cause glare to an observer located--outside the main beamare those which pass directly from the light sourceto the observer without reflection from theparabolicreflector. Thisinvention eliminates this glare without reducing the intensity of themain beamby'intercepting rays may be reflected to the surface of theroad as shown by providing the bottom of each shield with a reflectingsurface. The top of each shield should if opaque in the preferredembodiment of this invention be provided with a dead black finish inorder to prevent reflection from the top surfaces thereof to theobservers eyes.

It may be noted that=the shells near the axis of the reflector such as Iand 2 are more closely spaced than those at the top such as 4 and 5. Thereason for this may be seen by observing that in Fig. 1 the shell 2intercepts the ray R6 when it has passed approximately half way through,while theshell 5 intercepts the my R4 when it also has passed half waythrough the shell assembly, in spite of the fact that shell .5

is much farther from the adjacent shell 4 than.

shell 2 is from shell I.

It thus follows that the solid angle of light rays intercepted by anyshell is substantially proportional to the distance of said shell fromthe axis of the reflector P, so that they must be more closely spacednear the axis.

Overhead illumination While a set of shells used according to theprinciples of this invention greatly reduces the glare, illumination ofoverhead objects is not entirely eliminated since there is a certainamount of diffusion of rays even in a plain glass lens, and a certainamount of light is reflected from the tops of the shells unless thesurface is made very rough as well as black.

The illumination of overhead objects is improved without adding much' tothe glare by making the upper shells translucent. For best results thistranslucency is introduced 'only on the side of the filament remote fromthe approaching' driver in order to secure increased illumination ofoverhead objects on the right without throwing any glare toward anoncoming driver.

Application to spotlight In the case that it is desired to use a lamp asa spotlight, not necessarily pointed down at the road, and to minimizethe radiation of stray light toward a vehicle approaching on the left,one side of the lamp may be equipped with shields as shown at 24 and 25in Fig. 10. All

surfaces of these shells should be made dead I black.

A spotlight equipped with shells in this manner should be mounted onthat side of a vehicle which is remote from opposing vehicles.

Side illumination Figs. 2, 3, 6 and 7 show modifications of the shieldsin which one side of each shield l6, 2| is curved downward around theaxis of the reflector to minimize glare to an approaching driver whilethe other side is made horizontal in order to allow as much light aspossible to be'thrown to the right of each vehicle.

Another embodiment of this invention is shown inFigures 1, 4, 5, 8 and 9in which all of the shields are extended horizontally across the lamp inorder to throw more light to both sides of the road than in the otherconstructions.

It may be seen that the fundamental princlple is the proper utilizationof shells disposed in spaced relationship around the axis of saidreflector, every part of each surface being geometrically generated bylines substantially parallel to the central axis of the lamp.

Mounting of shells inside bulb The shells are for compactness mountedinside the bulb. In case a single filament incandescent lamp is used asa light source, as shown in Figs. 2 and 3 the shell l6 may be mounted soclose to the filament I! that satisfactory reduction of glare may beeffected with only one or two shields. The shells I! to l6 may bemounted in the press l9 by means of the elongated members l8 and- 20.

Another embodiment of my invention utilizes a plurality of shells suchas 2! and 2! mounted inside a double filament lamp bulb, as shown inFigs. 6 and 7. The lower filament 22 is turned on for driving when noother vehicles are approaching, and in order to provide the optimumillumination on both sides of the highway the shell II which isimmediately above said lower filament 22 is not curved around the sideof this filament. The upper filament 2t isturned on while passing othervehicles, and in order to avoid glare on the other driver the uppershell 2| is curved down around this filament 23. One filament may beoffset sideways from the other in order that the main .beam may be movedtowards the right when the upper filament is turned on. For optimumillumination of both sides simultaneously the arrangement of Figs. 1, 4,5, 8 and 9 may be used.

shells which should be used on any side of the axis is not critical but3 to 6 give the best results.

It is possible to get excellent reduction of glare with two shells, butif three are used suitably spaced it becomes much less critical toadjust the spacing from the light source. The

addition of more shells makes the spacing still highway, and theconverse for, the remaining countries.

In the foregoing specification and in the claims, the word bulb" hasbeen used as in common parlance to mean any hermetically sealed envelopeenclosing a light. source and adapted to 'allow light to escape, and isnot to be limited to any particular shape resembling a bulb in itsbotanical sense.

What I claim is:

1. In an incandescent lamp, the combination of a light source and aplurality of light intercepting shells disposed in spaced. relationshipextending forward of and above said light source parallel to a commonaxis and a sealed bulb enclosing all of said parts.

2. In an incandescent lamp, the combination of a light source and aplurality of opaque shells disposed in spaced relationship extendingforward from said light source parallel to a common axis passing throughthe light source, each shell having its outer surface with respect tothe common axis substantially light absorbing and a sealed bulbenclosing all of said parts.

3. In an incandescentlamp, a light source,

opaque and those remote therefrom being translucent. I l

4. In an electric headlamp the combination of an incandescent lightsource, light intercepting means including a part extending forward A ofand above said light source and being placed so that direct rays fromthe filament strike the light intercepting rays at a small angle and apart at one side of the first-named part adapted to intercept lightradiated laterally with respect to that intercepted by the first-namedpart and said light intercepting means having a reflecting surface onits surface exposed to the light source, and a sealed bulb enclosing theother H to upward forward component of light from the.

elements of said combination.

5. A double filament incandescent lamp comprising in combination twofilaments spaced in a plane transverse to a principal axis, lightintercepting means disposed in spaced relationship forward of at leastone of said filaments, a lateral portion of said light interceptingmeans being forward of one side of said filament and a sealed bulbenclosing all of-said parts.

6. An electric headlight bulbhaving an incandescent light source and aplurality of'light intercepting shells mounted within the bulb inoverlapping spaced relation, each of said lightintercepting shellsintercepting a part of the allel to a' common axis, thereby allowing therays parallel to the shells to pass substantially without interference.

7. An electric headlight bulb as described in claim 6, in which thesurfaceof the shells disposed toward the light source are reflecting,and those'disposed away from the light source and toward another shellare substantially non-refleeting, whereby to absorb light reflectedtoward the shell surface by another shell.

8. A double filament incandescent lamp comprising in combination twofilaments spaced one above another in a plane transverse to a principalaxis, light intercepting means comprised of a plurality of shellsdisposed in spaced relationship extending forward of and above one ofsaid filaments and parallel to said principal axis butnot so low as thelevel of the lowermost filament, and asealed bulb enclosing all of saidparts, whereby the beam emanating from light source, said shells beingsubstantially par- I the lower filament will have unobstructed upwardrays for a predetermined angle, but the beam projected by the upperfilament will have more of its upward rays intercepted by the shells.

9. An electric headlamp bulb as defined in claim 6, in which the shellsextend in a light intercepting manner farther to one side of said axis,measured angularly, than to the other side, whereby rays parallel tosaid principal axis are allowed to pass substantially withoutinterfeifence, and lateral rays beyond a limited divergence from saidaxis are transmitted without interception only on one side of said axis.

10. An incandescent lamp as described. in

claim 1, in which the light intercepting shells and the light source aresupported by supporting means common to both.

